This disclosure generally relates to sensor systems for aircraft, and more particularly, to a tip-back alarm system for an aircraft that detects when the aircraft has been loaded or unloaded in such a way that it is in danger of tipping back on its tail unless preventative action is taken.
An aircraft's initial, i.e., pre-flight, “weight and balance” determination is typically made while the aircraft is parked on the ground, and systems have been developed that are carried onboard the aircraft and that are capable of determining an aircraft's weight and balance automatically, in real time and continuously while it is being loaded. One such system is described in commonly owned U.S. patent application Ser. No. 11/560,451, filed Nov. 16, 2006, by M. Long et al.
Some onboard weight and balance measuring systems, such as that referenced above, may also include a “tip alarm” feature that measures nose gear loads, calculates the position of the aircraft's center of gravity (CG) and warns the personnel responsible for the loading of the aircraft if and when an aircraft tipping condition is imminent, so that appropriate corrective action can be taken to prevent the aircraft from tipping back.
Modern large aircraft, such as passenger and cargo jets, are typically provided with a tricycle landing gear, i.e., a nose gear disposed at the front of the aircraft and two or more main gears that are disposed aft of the aircraft's center of gravity and bilaterally symmetrical to its roll axis. Thus, an important consideration related to an aircraft's weight and balance, particularly for large aircraft capable of carrying heavy cargo and/or passenger loads, is that it not be loaded or unloaded in such a way that the change in loading causes the aircraft to “tip,” or tilt backward, i.e., rotate rearward about its main gear, such that the tail of the aircraft comes into contact with the ground and damages the aircraft.
However, since the primary function of such systems is to determine aircraft weight and balance, the existing systems that are also capable of providing a tip alarm feature are more complex, expensive, prone to in-service reliability problems if not scrupulously maintained, and are more difficult to calibrate than is necessary to implement a simple aircraft tip alarm function.
Accordingly, a need exists in the aviation industry for a tip alarm system for an aircraft that is inexpensive, light in weight, simple to install, use and service, yet which is also very reliable.